[ECO-4204] Remove code that's supporting older platforms (in v2)

[VeskeR]

Resolves #1538 , resolves #1332

See commit messages for more details.

[lawrence-forooghian]

There still seem to be some mentions of IE:

• ably-js/test/browser/connection.test.js

  Line 21 in 3d41166

  // IE doesn't support creating your own events with new

• ably-js/test/common/modules/testapp_manager.js

  Line 37 in 3d41166

  var xdr = new XDomainRequest(); /* Use IE-specific "CORS" code with XDR */

and of browser compatibility accommodations:

• ably-js/.eslintrc.js

  Line 22 in 3d41166

  // comma-dangle used for browser compatibility for browsers that don't support trailing commas

  (related to this I think)

Also, just a heads-up that writing "Resolves #1538 , #1332" in your PR description doesn't do what you think it does — you need to write "Resolves #1538, resolves #1332".

[VeskeR]

There still seem to be some mentions of IE:

Initially I wasn't sure if I wanted to remove IE code from tests that would lead to those tests not even being able to run on IE, but now looking at it again it really doesn't make sense to have this code present anymore. We're never going to test against IE and if someone else would try to run those tests - well it is going to break for a reason - we don't support IE anymore. So I will remove those mentions from test cases too.

and of browser compatibility accommodations:

Will take a look.

Also, just a heads-up that writing "Resolves #1538 , #1332" in your PR description doesn't do what you think it does — you need to write "Resolves #1538, resolves #1332".

Right, thanks!

[VeskeR]

Applied changes from conversations, removed IE mentions from tests and removed browser compatibility eslint rule

[VeskeR]

Added 2fc88a3 to remove node 0.8.x specific code, please review